Nonlinear pricing is pricing that is strictly proportional to the quantity purchased. For example, railroad tariffs are often based on weight, volume, and distance to be shipped; airlines offer frequent flyer bonuses based on miles flown; electric utilities charge different rates for different amounts of electricity used combined with the time it is used based on peak power demands. The book is divided into two parts. The first in a non-mathematical discussion of nonlinear pricing and the second part is more technical and is intended for readers interested in advanced topics.